French Drains & Drainage Systems in Stanwood, WA

Drainage & French drains in Stanwood: what to know

On level ground, a French drain needs a discharge that sits lower than the trench bottom. The trench falls steadily toward that outlet, and its stone is sized to carry the flow it will receive. Where a slope feeds water onto the lot, a curtain line intercepts it above the wet area. Where the county soil survey maps the Skagit series, the official description calls the soil poorly drained with a seasonal water table 6 to 24 inches down from November through March. We test that the outlet stays free of standing water through that window.

Roof water goes to a solid line with its own exit, kept apart from any perforated drain. The exit is picked from three options: soil that will take the flow, a city storm tie the city has signed off on, or a low point that does not flood a neighbor. Adjacent parcels and the street never serve as exits. Where the line crosses the public right-of-way, SMC 11.06.020 applies, and we ask the city which standards govern the crossing before the trench is cut.

Permits and rules in Stanwood

A drain in Stanwood is measured against the stormwater chapter and the grading section. SMC 17.140.030 has the public works director approve a stormwater site plan that includes a small parcel or large parcel erosion and sediment control plan, or a permanent stormwater quality control plan, and it says approvals such as a building permit wait for compliance. A trench deeper than two feet reaches SMC 18.830.020. We confirm the plan type with city staff, and we check each drain route on the survey before the trench is cut.

Rules change and vary by parcel, so we confirm the current requirements with the city before we start.

How we approach it

Survey the outlet before sizing the first trench
Lay the trench on a steady fall toward its exit
Keep roof lines solid and separate from perforated drains
Confirm the plan type before any digging starts

For the full process, see our Drainage Systems & French Drains page.

Questions from Stanwood homeowners

What outlets are acceptable for a Stanwood French drain?

Soil that will absorb the flow, a city storm tie the city has signed off on, or a low point that spares neighbors. Adjacent parcels and the street never serve as exits. Where the county soil survey maps the Skagit series, we test that the outlet stays dry through the November to March window.

Which Stanwood review applies when a drain crosses the right-of-way?

A crossing of the public right-of-way falls under SMC 11.06.020, which applies Stanwood’s street and utility standards. A trench deeper than two feet also reaches SMC 18.830.020, and we confirm the outcome with city staff before any excavation.

Can a drain stop water that runs down a slope into a Stanwood yard?

Often, when water comes off higher ground and gathers at the field edge. We chart the flow across the lot and propose a line only where a workable exit exists. Each proposal comes with the flow notes behind it, and the survey is kept with the job.